My mechanic was nice enough to let me shadow his guys while they did a heads/cam/intake install on my ‘02 C5. Great bunch of guys, made some new friends, but just had some questions about the last few steps where I’d like to see if the forum here agrees with my gut.
The build is based around TrickFlow 215 heads, milled to 61cc, using CamMotion Titan 4 cam, Harland Sharp SLS17 roller rockers and Johnson 2110R lifters.
My mechanic wasn’t fully familiar with the procedure for measuring proper pushrod length and preload, although he’s done an absolute ton of cam swaps and LS work before. He called in another mechanic who builds serious drag motors, races and seemed to really know the procedure that I’d only read about extensively. Using an adjustable length pushrod, feeler gauges, referencing the cam build sheet, doing some calculations, he arrived at a pushrod length of 7.425. Using the adjustable pushrod, the wipe pattern was perfect, centered.
I know that TrickFlow used 7.5” pushrods IF you don’t mill the heads and use you use stock lifters. Johnson lifters are apparently longer by a bit. .018” was milled from the heads to arrive at 61cc volume.
Pushrods should be shorter than 7.5 by a bit, but I couldn’t figure out why he arrived at a number so much shorter than I expected based on other’s experience and my calculations using amount milled, different lifters, etc.
I ordered the 7.425 lifters and we installed them today after testing the first set for wipe pattern. He says the pattern is fine, his engine builder guy that measured said it was fine, but I have my reservations on it. The wipe pattern while using the adjustable pushrod was perfect. This one, according to my research, indicates a pushrod that is too short. This would cause increased valve guide wear and less than optimal performance horsepower wise if the valves are not fully opened. What say the forum?

 

I can't tell anything from that pic. Too dark....

Having it centered is not as important as minimum sweep.

Try this one....


It works...

JIM

 

As mentioned above minimum sweep is more important that having it perfectly centered. one thing to keep in mind is that the pushrod length may not have been perfectly correct from the factory to begin with which may be why there seems to be more of a difference than you expected. i don't think there is any way you can spec out a pushrod length based on the parts being assembled without actually measuring once assembled. too many variables - block deck, heads, cam, rockers, lifters, head gasket thickness, valve stem length etc. etc. etc. ., . . . . .

here is what it should look like:

 

I used the Straub video to measure mine with the adjustable pushrod and this is the pattern I got. Chris Straub said this was good to go.